Cape Town – Eskom has announced a one-month delay in the return to service of Unit 1 at the Koeberg Nuclear Power Station, now expected to come back online by the end of August 2025 instead of July.
The 930MW unit is currently undergoing the second phase of its long-term operation maintenance programme.
The delay follows the discovery of defects in four steam generator tubes during detailed inspections, which Eskom described as part of its commitment to safety and quality.
“Our top priority is always the safety of our employees, the public and the environment,” said Bheki Nxumalo, Eskom’s Group Executive for Generation.
The defects were detected using eddy current inspections — a non-destructive testing method — and have since been successfully repaired by specialised international teams working alongside Eskom engineers. Major maintenance work, including the legally mandated 10-year Integrated Leak Rate Test (ILRT), was completed without issue, confirming the containment structure’s leak-tightness and structural integrity.
Koeberg Unit 1 return to service extended due to additional steam generator maintenance; passes structural integrity tests – no increased risk of loadshedding. pic.twitter.com/tYKNxIMcvF
— Eskom Hld SOC Ltd (@Eskom_SA) July 15, 2025
Eskom emphasised that the delay will not impact the risk of loadshedding this winter.
According to the utility’s Winter Outlook published on 5 May, unplanned outages would have to exceed 13,000MW for loadshedding to be triggered. As of 10 July, only 26 hours of loadshedding had occurred during the financial year.
Once maintenance is finalised, Unit 1 will undergo refuelling and final testing before being synchronised back to the national grid. Unit 2 remains fully operational with an impressive Energy Availability Factor (EAF) of 99.38% as of June 2025.
Koeberg’s two units collectively provide nearly 1,860MW, around 5% of South Africa’s electricity supply. Eskom reiterated that planned outages at the station are carefully staggered to ensure both units are never offline simultaneously.
The announcement comes as Eskom marks several major milestones in its broader generation recovery plan. These include the successful synchronisation of Kusile Unit 6 to the national grid in March 2025 and the return of Kusile Units 1–3 with repaired infrastructure by May. Additionally, Medupi Unit 4, offline since 2021, returned to service on 6 July.
These efforts, Eskom said, demonstrate its determination to stabilise power generation and meet the country’s electricity demand with improved reliability.
